The four sections of this paper provide an analysis of the structure of human memory. The first section, intended to provide a clear example of personal memory, examines a hypothetical episode in the life of an undergraduate student, and shows how one episode can give rise to three different forms of memory: personal, semantic, and rote linguistic. The second section develops a "botany" of important naturally occurring forms of memory and contrasts descriptions of six types of memory (personal, semantic, generic perceptual, motor, cognitive, and rote linguistic) with the traditional distinction between episodic and semantic memory. The third section decomposes the important naturally occurring types of memory and attempts to construct a table of the logically possible types of human memory. It organizes human memory in terms of the types of inputs and types of acquisition conditions and proposes an account of the possible forms of memory representation in terms of the intersections of these two factors. The final section relates the initial botany of memory to a more analytic classification scheme and discusses the mental processes involved in transferring information from procedural memory to semantic memory and the problem of the veridicality of mental images. (HOD)